In the manufacture of semiconductor devices, such as wafers to be diced into integrated circuit chips, it is necessary to monitor integrated temperature across the wafer in a heat cycle process. Examples of semiconductor processing involving heat cycles include, but are not limited to, rapid thermal annealing, physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma enhanced CVD (PECVD) and high density plasma CVD (HDPCVD).
Several disadvantages are associated with existing pyrometric monitoring devices and techniques, such as infrared (IR) temperature probes or thermocouple direct contact on wafers. First, these techniques generally only provide a temperature measurement of a single point on the wafer surface, rather than across an entire wafer. Second, these measurements provide instantaneous temperature values, rather than an integrated temperature measurement over the course of the entire heat cycle. Third, the measurement obtained by these techniques is often more of an environmental temperature rather than a measurement of the temperature across the wafer surface.
Still another disadvantage of existing pyrometric monitoring techniques is that IR probes do not work, or do not work effectively, when there are films or patterned structures on the surface of the wafer. Moreover, IR probes are ineffective in low temperature regimes and, with aluminum-copper wiring, which is currently the standard wiring in semiconductor integrated circuits, the desired temperature range is generally 350 to 400 degrees Celsius, a range in which IR probes are ineffective. Yet another disadvantage is that while existing pyrometric techniques work well in a laboratory environment, they do not function well in the manufacturing environment due to conditions such as wafer backside variations and degradation of the optic fiber of the pyrometric tool.
Therefore, there exists a need to develop an easy and effective method and device to accurately monitor integrated temperature across a wafer in a semiconductor processing heat cycle.